1. Field of the Invention
The present invention relates to a board adapter for electrically connecting an electrical card connector to a mother board, and particularly to a board adapter which sufficiently resists electromagnetic interference (EMI).
2. The Prior Art
A well-known, generic electrical connector is equipped with a shielding means such as a conductive shell and a grounding means connected to some grounding circuits of the mother board on which the electrical connector is mounted to resist an electromagnetic interference (EMI) and an electrostatic discharge (ESD) usually resulting from a number of high frequency electrical elements next to the connector. Such designs regarding grounding means which protect the connector can refer to the disclosures of Taiwan Patent Application Nos. 80,207,449, 81,216,447, 81,217,278, 82,205,600, 83,202,199, 83,107,162, 83,281,401, 77,208,107, 84,213,585, 84,213,586 and 85,210,940.
For an electrical card connector receiving a corresponding electrical card such as a memory card or a I/O card, a board-like adapter with a number of circuits is presently equipped to transmit Input/Output messages between the electrical card connector and the mother board. However, the board-like adapter is often exposed outside the shell means and the grounding means of the electrical card connector whereby the board-like adapter may suffer an electromagnetic interference resulting from high frequency electrical elements adjacent to the board-like adapter. In addition, another origination of the EMI problem is happened in the board-like adapter. Since some transmission traces presented on opposite surfaces of the conventional board adapter have the same polarity, adjacent transmission traces may electromagnetically interfere with each other's signal. This phenomena is commonly referred to as "crosstalking". Furthermore, the conventional board-like adapter is merely adapted to bear an unitary current, i.e. a 5 V induced current, and has no an adjustable capability to bear the variable voltages from different voltage outputs of the power supply.
Accordingly, to resolve the above disadvantages, an object of the present invention is to provide a board adapter which is designed with a transforming means consisting of a first power trace and a second power trace to separately bear two different strength voltage induced current wherein the first power trace is adapted to bear a high voltage induced current and the second power trace is adapted to bear a low voltage induced current. When the first power trace bears the high voltage current, the second power trace is transformed into a grounding trace to provide the first power trace with grounding protection, and vice versa.
Another object of the present invention is to provide a board adapter for electrically connecting an electrical card connector to a mother board, which has a first grounding means and a second grounding means for providing the signal holes, the signal traces and the electrical connector with grounding protection wherein the second grounding means consists of a plurality of grounding traces which each is alternately juxtaposed with every two of signal traces.